Generally speaking, capsules for infusion products basically comprise a cup-like container, constituting the capsule proper, with or without a filter element inside it and having an inlet opening which is closed by a respective lid. A measured quantity of product—for example, coffee—is filled into the container in substantially known manner, in order to make a beverage by infusion of water through the capsule itself.
Machines for making capsules of this kind comprise a plurality of processing stations, including a station for filling, or dosing, the product into the container and a weighing station for checking that the container is correctly filled.
An example of a machine for making capsules for infusion products is described in patent application WO2013/035061.
In this machine, the capsules being processed are housed in respective seats made on brackets which feed the capsules along a predetermined path through the processing stations.
More specifically, in the filling station, the capsules—or rather, the containers—are made to pass under the filler, for example of the screw type, from which a certain quantity of product is allowed to drop.
Downstream of the filling station, along the feed path, in the weighing station, the filled capsules are extracted from the respective seat by means of a suitable lifting system in order to release them from the supporting bracket.
The weight of the capsules is then checked by means of loading cells built into the lifting system.
After being weighed, each capsule is lowered back into its seat on the bracket and fed to the subsequent stations.
Generally speaking, prior art capsule making machines comprise a feedback control system configured to control the filling station based on the weight values measured, that is to say, to control the filling of the capsules which follow those previously filled and weighed.
One disadvantage of prior art capsule making machines is due to the fact that a relatively long time is necessary to allow the product to settle inside the capsule after the capsule has been lifted and before it can be weighed.
Moreover, the lifting system must be free of the frame or base of the capsule making machine itself so that the vibrations and movements of the machine do not cause inaccurate measurements.
In practice, that means the lifting system and the loading cells constitute a self-contained unit separate from the machine frame and the architecture of the machine in its entirety is thus relatively complex and expensive.
In this context, the main technical purpose of this invention is to overcome the above mentioned disadvantages.